In the case of danger, alarm, fire, smoke formation, threats, etc., the presence of clearly visible signs in premises is extremely important, for example for indicating the nearest escape route or the location of fire extinguishing equipment. According to the colour requirements stipulated by the appropriate authority, the signs shall have one or more white, standardised symbols on red or green background.
Some of the existing afterglowing safety signs are used, inter alia, to indicate and display escape routes and emergency exits and to indicate the location of fire extinguishing equipment. However, the afterglowing pigments used do not exist in the colour shades needed to obtain an optimal colour reproduction both in daylight and, with a coloured afterglow, in the dark. The solution to this problem has so far been to accept that these signs show afterglowing symbols only in the dark, in which case their background colour has been perceived as black. Thus, the colour requirements for these afterglowing safety signs are met only in daylight and in lit places, since the afterglowing pigments available do not completely fulfil the requirements both in daylight/lit spaces and in the dark.